Adjustable thresholds are known in the prior art and have for their purpose to compensate for unevenness and lack of squareness in doors and door frames, as well as to provide an improved doorway seal. Some examples of the patented prior art are shown by U.S. Pat. Nos. 3,374,579; 3,690,037 and 3,762,100.
The general objective of this invention is to improve on the prior art adjustable thresholds by rendering them less complicated and therefore less costly and by increasing their efficiency of operation and ease of installation.
Generally, the devices of the prior art have not been widely accepted because of undue complexity and cost and because they are difficult to install and properly adjust and lack the sturdiness of construction required for long service with practically no maintenance. The present invention seeks to overcome these and other deficiencies of the prior art, and various features and advantages of the invention will become apparent during the course of the following description.